Threading tool



0C? 4:, 1932. J LAMQND 1,881,281

THREADING TOOL Filed 001;. 6', 1931 INVENTOR Patented Oct. 4, 1932 UNITED-STATES Join: LAmonn, or mson max, rmmvanu.

TENT" oF1- 1c1z mmnme 11:001.;

' Application filed october e, 1931. sum it. 567,205.

being operated on to be so defective as to require scrapping of the work, or at least cause undesirable rou'ghhess on the threaded work. Not only do large quantities of workhave to be scrapped, but the threading tools v ing of so-called stickers int e cutting tool is avoided.

-vide a threading tool of wi produce both a roughing cut and a fin-, ishing cut by a single continuous operation.v

have to be frequently" reconditioned or entirely replaced.

One object of my invention is to provide a threading tool of such fo that the lodg grooves of the Another object of my in ch form that it Still another object of my invention is to provide a threading tool of such'form that it may be employed for high speed or mass production, without requiring frequent ieconditioning or renewal, thereby reducing frequenof interruptions incident to changing t reading tools.

Some views embodying invention are k shown in the accompanying drawing wherein Figure l-is a sideview of a tap; Fig. 2 is a fragmentary view thereof, on an enlarged view showing more clearly the scale; Fig. 3 isa crosssectional view of the structure of Fig.2; Fig. 4 is relief provided at the roots of the cutting threads; Fig. 5 is an end view of a ipe thread chaser, and Fig. Sis a'side-viewt erect. U 7

Referring first to Figs. 1 to 4, I show a tap which in its general contour may be of somewhat standard form, but wherein the cutting teeth or .threads have, been me 'fied accordto ing to my invention.- The cut teeth or edges and sides,

ention is to pro- ..corporating my invention therein, 7

its edge naran exaggerated root surfaces to the lead threads are out than at 1Q, instead of threads 5 are formed on the lands 6in sonicwhat. the usual manner, they being shown as having the usual reliefon their peripheral for about one-half thedistance between the face? on each land and the heel 8 thereof, the point at which'the relief commences being at the line 9' (Fig. 3). In some instances, manufacturershave formed the relief beginning at a point nearer to the face 7,;Jin order to reduee'tendenc for the lodgment of stickers between the sides of the teeth 5, but such structures are likely to pro.- duce threads of wavyspirals. 1

v The tops, sides and 5 are usually relieved in a proximatel equal degree, but I have foun that by rehe the rootpr bottom of the groove between the threadsto a greater extent,-,as indicated by- -the numeral 10, the lodging of stickers at the y root avoided. Preferably, provide this relief along the line 10 throughout substantially thefull. length of the root, commenccontour instead of true J roots of the'threads ing. at approximately the face 7 of the land, while the relief at the tops and sides of the 7 threads 5 may begin at the half-way point 9 or at any ot er suitable int. The dotted line 11 indicates the usua amount of relief at the root, but, as indicated by the line 10,- V

I cut'the root deeper, to perhaps the extent to considerably greatere xtent, at the heel '8 of the land. I Y

The additional relief at the root may be formed-in any suitable manner. In providof two-thousandths of an inch or even to a ing standard cutters for the'purpose of in.-

h I may'sim' i take a grinding' tool avmg' i oiiver or of smaller angularity than the tool which was ori all teeth,- so that e grmding tool will cut the agreater depth without materiall cutting away the sides of the thre 5. v v 1 a In order to produce a roughing cut, I relieve the roots of the lead threads 12 of the tap in substantially the same manner as in the case p of relief provided at 10, but the roots 13 of tea greater depth having the root botemployed to cut the go When the lead threads or roughing threads become worn, it is necessary only to grind the face of the land, from the first lead thread 12 to the last lead thread, in order to recondition the roughing portion of the tap, itnot being desirable or necessary to grind the face of the land at the portion thereof containing the full or finishing threads, since to do so,

would prevent the cutting of properly- 1 formedthreads in the material being threaded i It has beenifound that threads cut with dies I tops thereof, and the roots being cut more deeply in the roughing portion of the tool, the

roots being relieved from the face. of the land to the heel thereof. '5. A threading tool having a roughing portion and a full-thread cutting portion, both having teeth Whose tops, sides and roots are relieved, the roots of the teeth in the roughing portion being relieved to a greater degree than are thesides and the tops. thereof.

In testimony whereof I have hereunto set my hand.

JOHN LAMOND.

having the additional root relief above-described, are much smoother than threads cut with various standard types of taps, and that the tapsmay be employed over a very much longer period of time than the older types of tapsywithout requiring reconditioning or replacement. Further, the scrap loss of work produced by my taps is reduced to a minimum. Referring to Figs; 5 and 6, I show a pipe thread chaser 15, which is a segment of a pipe threading die. 'ljhe chaserlfihascuttingteeth or threads 16 whose roots 17 are relieved from I the faces 18 'of the lands, to the heels there-.

of, and to a greater extent than the edges and sides of theteeth, as in the case of Figs. 1 to 3.

The lead threads 19 serve asroughing ele- Inents as in the "case of the threads 12 of Fig.

' 2, and have their roots relieved along theirentire lengths,'and to a greater depth than the tops and sides of. the teeth.

It will be understood that the invention is applicable to various other forms of threadthan said tops and sides.

ing devices for cutting either internal or external threads on pipe couplings, pipes, etc.

I claim asjmy invention r 1. A threading tool having cutting teeth relieved at their tops and sides andhaving the roots thereof relievedto a greater degree 2. A threading tool having cutting teeth relieved at their tops and sides and having theroots thereof relieved to a greater degree than said tops and sides, the said root relief being provided from the face of the land to the heel thereof.

,3. A threading tool (having cutting teeth relieved at their tops and sides and having the roots thereof relieved toi a greater degree than "said tops and sides, the said root relief being provided from the face of the land to the heel thereof, and the sidesand faces of the teeth being relieved from a point substantially midway between the face of the land and the .heel thereof. i

4. A threading tool 'having a roughing portion and a full-thread cutting portion, both having teeth whose tops, sides and roots are relieved, the roots of the teeth being relieved .to agreatei' degree than are the sides and the 

